During the past decade substantial advances in processing speed, memory size and software have occurred in computer technology. Similar advances have resulted in highly sophisticated communication systems. These developments have enabled digital electronic methods to become a practical photographic image processing technique. For example, a recently developed change detection system (Ref. 1) is capable of processing 400,000 image points per second. This and other digital image processing systems generally result from special purpose applications of algorithms developed on large scale, general purpose digital computers.
"Sample Interval and Spot Shape For Digital Image Processing Systems", Proc. SPIE 0046, Image Assessment and Specification, (1 June 1974); doi: 10.1117/12.953999; https://doi.org/10.1117/12.953999